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Tracing Instrumentation using OpenTracing API (

Project description

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# opentracing-python-instrumentation

A collection of instrumentation tools to enable tracing with
[OpenTracing API](

## Module

Make sure you are running recent enough versions of `pip` and `setuptools`, e.g. before installing your project requirements execute this:

pip install --upgrade "setuptools>=29" "pip>=9"

The module name is `opentracing_instrumentation`.

## What's inside

### Supported client frameworks

The following libraries are instrumented for tracing in this module:
* `urllib2`
* `requests`
* `SQLAlchemy`
* `MySQLdb`
* `psycopg2`
* Tornado HTTP client
* `redis`

### Server instrumentation

For inbound requests a helper function `before_request` is provided for creating middleware for frameworks like Flask and uWSGI.

### Manual instrumentation

Finally, a `@traced_function` decorator is provided for manual instrumentation.

### In-process Context Propagation

`request_context` implements thread-local based context propagation facility.

## Usage

This library provides two types of instrumentation, explicit instrumentation
for server endpoints, and implicit instrumentation for client call sites.

Server endpoints are instrumented by creating a middleware class that:

1. initializes the specific tracer implementation
2. wraps incoming request handlers into a method that reads the incoming
tracing info from the request and creates a new tracing Span

Client call sites are instrumented implicitly by executing a set of
available `client_hooks` that monkey-patch some API points in several
common libraries like `SQLAlchemy`, `urllib2`, Tornado Async HTTP Client.
The initialization of those hooks is usually also done from the middleware
class's `__init__` method.

There is a client-server example using this library with Flask instrumentation
from opentracing-contrib:

Here's an example of a middleware for [Clay framework](


from opentracing_instrumentation.request_context import RequestContextManager
from opentracing_instrumentation.http_server import before_request
from opentracing_instrumentation.http_server import WSGIRequestWrapper
from opentracing_instrumentation.client_hooks import install_all_patches

class TracerMiddleware(object):

def __init__(self, app, wsgi_app):
self.wsgi_app = wsgi_app
self.service_name =

CONFIG.app_name = self.service_name

self.wsgi_app = create_wsgi_middleware(wsgi_app)

def __call__(self, environ, start_response):
return self.wsgi_app(environ, start_response)

def init_tracer(self):
# code specific to your tracer implementation

def create_wsgi_middleware(other_wsgi, tracer=None):
Create a wrapper middleware for another WSGI response handler.
If tracer is not passed in, 'opentracing.tracer' is used.

def wsgi_tracing_middleware(environ, start_response):
# TODO find out if the route can be retrieved from somewhere

request = WSGIRequestWrapper.from_wsgi_environ(environ)
span = before_request(request=request, tracer=tracer)

# Wrapper around the real start_response object to log
# additional information to opentracing Span
def start_response_wrapper(status, response_headers, exc_info=None):
if exc_info is not None:
span.add_tag('error', str(exc_info))

return start_response(status, response_headers)

with RequestContextManager(span=span):
return other_wsgi(environ, start_response_wrapper)

return wsgi_tracing_middleware

And here's an example for middleware in Tornado-based app:

class TracerMiddleware(object):

def __init__(self):
# perform initialization similar to above, including installing
# the client_hooks

def __call__(self, request, handler, next_mw):
request_wrapper = http_server.TornadoRequestWrapper(request=request)
span = http_server.before_request(request=request_wrapper)

def next_middleware_with_span():
yield next_mw()

yield run_coroutine_with_span(span=span,


def run_coroutine_with_span(span, func, *args, **kwargs):
"""Wrap the execution of a Tornado coroutine func in a tracing span.

This makes the span available through the get_current_span() function.

:param span: The tracing span to expose.
:param func: Co-routine to execute in the scope of tracing span.
:param args: Positional args to func, if any.
:param kwargs: Keyword args to func, if any.
def mgr():
return RequestContextManager(span)

with tornado.stack_context.StackContext(mgr):
return func(*args, **kwargs)

## Development

virtualenv env
source env/bin/activate
make bootstrap
make test


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